1. Field of the Invention
The present invention relates to a feed screw apparatus, and in particular, to a feed screw apparatus having a compact linear guide means provided to a part of the feed screw apparatus.
2. Description of the Prior Art
A prior art feed screw apparatus having linear guide means combined therewith is disclosed, for example, in Japanese Patent Laid-Open Publication No. 61-61362.
This apparatus comprises a feed screw shaft having a spiral groove formed in the outer surface, a linear guide rail provided on the feed screw in parallel therewith, and a nut block, including a linear guide means, fitted to the linear guide rail and movable in the axial direction, and a nut section, formed integrally with the linear guide means, engageable with the feed screw shaft. The rotational movement of the nut block with respect to the feed screw shaft is prevented by the linear guide means.
By combining the linear guide means with the feed screw, it is possible to simply guide, for example, a table of a machine tool linearly. Additionally, a compact feed unit can be formed by positively and arbitrarily driving, stopping, and positioning utilizing a driving device. In such a combination, since the linear guide means and the feed screw can be worked at the same reference plane, excessive man-hours are not necessary in assembling and adjusting, as in the prior art. Accordingly, an advantage is provided in that the scope of application can be expanded to various fields of application including robotics, automatic transportation devices, and the like.
However, the prior art apparatus mentioned above is a simple combination of the feed screw and a linear guide device as the linear guide means, and is constructed by merely attaching a ball screw device to a slider of a linear guide device. As a result, for example, the size, in a height direction, is substantially equal to a sum of heights of the prior art linear guide device and the ball screw, and, as such, a problem is encountered in that it is impossible to make it small in size and light in weight. Moreover, another problem is posed in that excessive time and large expenditures are required for adjustment, in order to maintain the assembling accuracy.